1. Field of the Invention
The present invention relates to the so-called indwelling injector needle having wings and a needle body and, more particularly, to an injector needle held in a protector having wings such that when the needle body slides into the protector after use, the needle edge is automatically retracted therein to protect a user from erroneously piercing his or her skin with the edge.
2. Description of the Prior Art
Conventional medical needles are usually separable from protective members designed to accommodate the needles. Users of those medical needles often have erroneously pricked their fingers with the edges of used needles, when the latter were restored in the protectors held by their fingers. Thus, there is and has been a possibility that the users might be infected with acquired immune deficiency syndrome (AIDS) or hepatitis. Some injector assemblies have been proposed or provided to prevent such accidents. For example, U.S. Pat. No. 5,120,320 discloses an injector assembly that comprises a protector integrally connected to an indwelling needle which has wing-shaped members. In this assembly a used needle is allowed to slide backward into the protector along a pair of guide slits formed longitudinally thereof so that the used needle's edge is hidden in the protector. In another assembly shown in Japanese Unexamined Patent Publication No. 1-212561, an indwelling needle is combined with a protector having wings. Due to a positioning mechanism intervening between the needle and the protector, the protector can slide toward the needle so that the needle edge is enclosed so as not to injure the user.
The wings integral with the needle body shown in U.S. Pat. No. 5,120,320 are secured to a patient's skin by means of adhesive tape or the like. Such an indwelling needle cannot be retracted in situ into the protector, unless the tape is torn off and the needle is withdrawn from the patient's skin. Further, the needle body shown in Japanese Unexamined Patent Publication No. 1-212561 often moves backward relative to the protector, due to the resistance of the skin being pricked with the needle. In addition, the needle body tends to slip off, when it is manually pulled backward to retract the needle edge into the protector.